The former lover of Seven West Media boss Tim Worner has been ordered to foot the company's legal bill after the Supreme Court found she made allegations she "could not substantiate" and acted unreasonably in her legal battle with the media company.

Amber Harrison, a former executive assistant at Seven, has been at the centre of an ugly court battle with the company since she went public in December last year with embarrassing details of her 18-month affair with Mr Worner.

In a judgment delivered on Monday, Justice John Sackar said Ms Harrison's conduct had been "unreasonable" and it was "necessary and appropriate" to order her to pay Seven's costs on an indemnity basis, which is higher than the costs typically awarded in legal disputes and would cover its entire bill.

The costs are likely to be in the order of hundreds of thousands of dollars.

"These proceedings have, from the outset, been engulfed in a vitriolic atmosphere," Justice Sackar said.

"The allegations from both sides, whether entirely true or not, have often been personal, scandalous, and sadly ripe for media and public consumption."

Justice Sackar said "numerous epithets" had been used to describe Ms Harrison and her motivations but he did not "feel the need to join in the histrionics".

In a statement on Twitter after the judgment was delivered, Ms Harrison took aim at "brutal corporate bullying and lawfare" and said Seven knew the order "would bankrupt me".

But Seven welcomed the decision and said it "[looked] forward to putting this matter behind us".

Ms Harrison left Seven in late 2014 after signing two deeds which provided for a series of payments totalling hundreds of thousands of dollars to be made to her on the basis she did not speak about the company or the relationship.

Seven took her to court in February seeking a gag order holding her to those agreements, after she set up a Twitter account to air her grievances.

Justice Sackar said Ms Harrison filed a cross-claim against Seven in March "mounted on allegations she could not substantiate" and continued to run that case in the face of adverse preliminary orders, settlement offers and "a complete lack of evidence".

The Supreme Court granted a temporary gag order against Ms Harrison in February and the parties were due to fight it out last week as Seven sought to make the order permanent.

But Ms Harrison capitulated at the 11th hour and said she would agree to the court making a permanent gag order.

Justice Sackar said Ms Harrison had been given "every opportunity" to bring the court case to an end and it was a "pity" she had not agreed to the orders at an earlier stage.

He said it was clear Ms Harrison had "engaged in numerous breaches" of a deed of release signed in November 2014 and her employment contract, "and these breaches have been persistent and flagrant".

He rejected her argument she was no longer bound by the deed because Seven had suspended payments to her, noting that she had not complied with her obligations to hand over electronic devices and records.

She had argued that Seven should be forced to foot its own bill.

The media company had offered to settle the proceedings on February 27 but Ms Harrison "did not take up this offer", Justice Sackar said.

He rejected her argument that an indemnity costs order would amount to punishing her for "taking a stand" and said it was an appropriate order to "compensate [Seven] ... for the unreasonable costs incurred in these proceedings".

Justice Sackar said Ms Harrison's statements to the media were a "clear breach" of her obligations to remain silent, and she had also breached an agreement not to take legal action against the company.

He ordered Ms Harrison to return all company property and made a series of declarations that she had breached her obligations under the deed of release she signed before leaving the company.